Compressor is one such device which is used for several purposes on a ship. As the main aim of the compressor, as the name suggests, is to compress air or any fluid in order to reduce its volume. Some of the main applications of compressors are main air compressor, deck air compressor, AC compressor and refrigeration compressor. In this article we will learn about air compressors and its types.
Air Compressor produces pressurized air by decreasing the volume of air and in turn increasing its pressure. Different types of air compressors are used according to the usage.
Types of Air Compressors
There are mainly four types of compressors:
- Centrifugal compressor
- Rotary vane compressor
- Rotary screw compressor
- Reciprocating air compressor
However, on ship reciprocating air compressor is widely used.
Uses of Air Compressor on Ship
On board a ship, compressed air is used for several purposes. On the basis of application, different air compressors are kept for a particular usage. Normally, air compressors on board ships are:
- main air compressor
- topping up compressor
- deck air compressor
- Emergency air compressor
- Main air compressor
Main air compressor is used for supplying high pressurised air for starting of main and auxiliary engines. The pressurised air generated by the air compressor is stored in air storage bottle. These are high capacity compressors and the air pressure that is required from these compressors to start the main engine is 30 bars.
Control air is also supplied from air bottle through a pressure reducing valve and a control air filter. Normally they are twice in number and can be more than that for redundancy.
Topping up compressor takes up the lead to cover up for the leakage in the system. This means that as soon as the air pressure in the system goes below a particular level, the topping up compressor replenished the system with pressurized air.
Deck air compressor
Deck air compressor is used for deck use and as service air compressor and might have a separate service air bottle for the same. These are lower capacity pressure compressors as pressure required for service air is in between the range of 6 to 8 bar.
Emergency air compressor
Emergency air compressor is used for starting auxiliary engine at the time of an emergency or when the main air compressor has failed for filling up the main air receiver. This type of compressor can be motor driven or engine driven. If motor driven, it should be supplied from emergency source of power.